This invention relates to personal computers, and more particularly to personal computer power supplies for supplying electrical power to electrically operated components which manipulate or store digital data.
Personal computer systems in general and IBM personal computers in particular have attained widespread use for providing computing capability to many segments of today's modern society. Personal computer systems can usually be defined as a desk top, floor standing, or portable microcomputer that consists of a system unit having a single system processor and associated volatile and non-volatile memory, a display monitor, a keyboard, one or more diskette drives, a fixed disk storage, and an optional printer. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. These systems are designed primarily to give independent computing capability to a single user and are inexpensively priced for purchase by individuals or small businesses. Examples of such personal computer systems are IBM's PERSONAL COMPUTER AT and IBM's PERSONAL SYSTEM/2 Models 25, 30, 50, 55, 60, 65, 70 and 80.
These systems can be classified into two general families. The first family, usually referred to as Family I Models, use a bus architecture exemplified by the IBM PERSONAL COMPUTER AT and other "IBM compatible" machines. The second family, referred to as Family II Models, use IBM's MICRO CHANNEL bus architecture exemplified by IBM's PERSONAL SYSTEM/2 Models 50 through 80. The Family I models typically have used the popular INTEL 8088 or 8086 microprocessor as the system processor. These processors have the ability to address one megabyte of memory. The Family II models typically use the high speed INTEL 80286, 80386, and 80486 microprocessors which can operate in a real mode to emulate the slower speed INTEL 8086 microprocessor or a protected mode which extends the addressing range from 1 megabyte to 4 Gigabytes for some models. In essence, the real mode feature of the 80286, 80386, and 80486 processors provide hardware compatibility with software written for the 8086 and 8088 microprocessors.
Electrical power for energizing the components of such personal computers is conventionally supplied by power supplies which use control logic, switching transistors, power transformers, rectifiers and filters to convert electrical power from an available line voltage and current, such as the 110 volt 60 hertz current supplied in the United States, to the direct voltages and currents required for operation of the personal computer. It has been conventional to control operation of such power supplies by switching the supply voltage to the power supply. In the example given, such switching is accomplished by turning on and off the 110 volt 60 hertz mains supply current. As will be appreciated, such switching of the generally supplied service voltage requires switches which are at least somewhat substantial as compared to the significantly lower voltages and current typically used with the operating components of the personal computer.
It has been proposed heretofore, as in Summerlin U.S. Pat. No. 4,723,269, to use a lower level voltage to control the operation of a personal computer power supply. In the Summerlin disclosure, to which the interested reader is referred, a telephone ring detector acts through optically coupled semiconductor devices to control passage of the relatively high voltage supply current. However, such circuitry continues to require manual control over computer power to be exercised by manipulation of a relatively high voltage switch.